The year is 1970. A young girl called Sarah is walking along the boundary of a disused naval base in St. Oswald beyond a sign which clearly says "Ministry of Defence. Keep Out" She stops as she hears a strange electronic noise. She wanders closer to the base and is seen by Tom Ferris, a farm labourer. Ferris calls out to her but she is mesmerised by the strange sound. She feels out to an invisible barrier that appears to be set between a series of redundant concrete fence posts... and suddenly vanishes into it! The labourer stumbles disbelievingly to the remains of the fence but finds nothing to credit what he has just witnessed save a discarded handkerchief.

Liz and Simon emerge from the time barrier not in 1970, as they expect, but in an icy landscape. In the biting cold, they both collapse.

Back in 1970 Jean is sharing the experience and is shivering. Frank notices this but Traynor comments that she isn't actually cold. Franks wonders what has happened to Liz and Simon and says that in order to return to the present they only had to crawl through the hole in the fence. Traynor states that they're still learning about the time barrier.

A red-suited figure crosses the icy landscape and makes an examination of two large ice blocks, which have gauges on the side. The figure notices the two unconscious figures and lifts Liz, carrying her back across the wasteland to a sliding door that lets into a futuristic-looking installation. A woman meets the figure and he explains that there is 'another one outside.'